Stirling cycle machine and system



Aug. 12, 1969 k. P. JOHNSON 3,460,3 4

STIRLING CYCLE MAQHINE AND SYSTEM Filed Dec. 15, 1967 9 Sheets-Sheet 1 l NVEN TOR. KENNETH P JOHNSON ATTORNEYS Aug. 12, 1969 K. P. JOHNSON v 3, 6 3

STIRLING CYCLE MACHINE AND SYSTEM Filed Dec. 15, 19 67 9 Sheets-Sheet a v 4 2 T INVENTOR.

COMP V KENNETH R JOHNSON 3 1% m/M/ax fij h kW F/G. 5A

ATTORNEYS 2, 1969 K. p. JOHNSON 3,460,344

STIRLING CYCLE MACHINE AND SYSTEM Filed Dec. 15, 1967 9 Sheets-Sheet 3 INVENTOR. KENNETH P. JOHNSON F/G 6 444/, WWW

MM fi ATTORNEYS Aug. 12, 1969 K. P. JOHNSON 3,460,344

STIRLING CYCLE MACHINE AND SYSTEM Filed Dec. 15, 1967 9 Sheets-Sheet 4 CO 3 INVENTOR. v T 4 (#19 3 BY KENNETH P. JOHNSON v s fi ofl z .F/G. 9 F/G. 95 MI ATTORNEYS Aug. 12, 1969 I K. P. JOHNSON 3,460,344

STIRLING CYCLE MACHINE AND SYSTEM Filed Dec. 15, 19s? 9 Sheets-Sheet 5 r J J. i A R R H H L T T r J .L i. Ii a i :1 L C x T H H --n g r R a R i 29w i 6 //A c c HA 1 T 1 x 1/5 "5 115 f M I -2oe E I 282 I l/D if 278 F/.

276 277 INVENTOR.

- KENNETH P. JOHNSON ATTORNEYS Aug. 12, 1969 K. P. JOHNSON 3,460,344

STIRLING CYCLE MACHINE AND SYSTEM Filed Dec. 15, 1967 9 Sheets-Sheet BUFFER CHAMBER l4l OIL TRAP INVENTOR. KENNETH P. JOHNSON BY /2 %4 4%4/ M IV /M ATTORNEYS Aug. 12, 1969 K. P. JOHNSON 3,460,344

STIRLING CYCLE MACHINE AND SYSTEM Filed Dec. 15, 1967 9 Sheets-Sheet 7 T V 2 T I T v V lNVENTORL- 5 KENNETH P. JOHNSON v S MMW F/G. I5A F/G I55 %/ML;7 M

ATTORNEYS Aug. 12, 19639 K. P. JOHNSQN 3,460,3

STIRLING CYCLE MACHINE AND SYSTEM Filed Dec. 15, 1967 9 Sheets-Sheet s I6l\ I58 V HA I i H I H R I69 R I 51/70 5 F/G /7 I84 I74 I INVENTOR. I KENNETH P JOHNSON F/G. l6 W MQ flM X W ATTORNEYS Aug. 12, 1969 K. P. JOHNSON 6 STIRLING CYCLE MACHINE AND SYSTEM Filed Dec. 15, 1967 9 Sheets-Sheet 9 TO CY LE WORKING L FL UIO VOL.-\ 500 2 500 PSI.

P CYCLE (PS1) 500- PRESSURE LINACTIVE VOL. PRESSURE I,OOQ

'F/G l9 TO CYCLE WORKING FLUID voL.

INVENTOR. KENNETH P. JOHNSON ATTORNEYS United States 3,460,344 STIRLING CYCLE MACHINE AND SYSTEM Kenneth P. Johnson, 124 Castle Crest Road, Walnut Creek, Calif. 94529 Filed Dec. 15, 1967, Ser. No. 691,054 Int. Cl. F02g J/O4, 3/00; F01c 9/00 U.S. Cl. 6024 21 Claims ABSTRACT OF THE DISCLOSURE This invention pertains to mechanism for displacing, compressing or expanding a gas working fluid and is particularly useful in providing a Stirling cycle engine.

As is well known, a Stirling cycle engine uses gas as a working fluid and, if it is single acting, requires a minimum of two reciprocating pistons operating within either one or two cylinders. (US. Patent 2,590,519 Hot-Gas Engine or Refrigerator F. K. Du Pre, Mar. 25, 1952. US. Patent 2,397,734 Engine P. L. Goebet et al., Apr. 2, 1946.) These engines are generally classified as being opposed piston engines or displacer piston engines.

In order to construct double acting machines of the opposed piston type it is necessary to utilize a minimum of three or four pistons and three or four cylinders. (US. Patent 2,480,525 Multicylinder Hot Gas Engine F. L. Van Weenen, Aug. 30, 1949.) Multiple cylinder arrangements of displacer piston engines have been devised but they are single acting machines which employ a minimum of four pistons and two cylinders (US. Patent 3,074,229 Hot-Gas Reciprocating Machine and System composed of a plurality of these machines H. B. Baas et al., Jan. 22, 1963).

Multiple cylinder machines are bulky and require relatively long passages to interconnect working chambers which increases the dead volume in the active working fluid system. Dead volume is defined as that volume (heat exchangers, connecting ducts, and piston end clearance) in the active working fluid system which is not swept by the pistons. Engine power density is significantly sensitive to dead volume and inversely proportional to it.

In addition, Stirling cycle machines which employ reciprocating pistons characteristically exhibit problems relative to minimizing leakage of gas working fluid into the crankcase. (US. Patent 2,982,088 Gas Leakage Prevention Means for Hot Gas Reciprocating Apparatus R. J. Meijer, May 2, 1961.) The reciprocating piston rods provide a pumping action to pump high pressure gas into the crankcase which necessitates use of elaborate seal arrangements. Even when a buffer chamber is used between the working pistons and the crankcase or when the crankcase is pressured, this pumping action of the reciprocating piston rods persists.

Thus, a steady make-up of working fluid is required and the crankcase lubricant often finds its way into the working chambers changing the characteristics of the working fluid and contaminating the heat exchangers. Typically, the connecting rod seals must seal a pressure diflerential of 1,500 p.s.i.- -OO p.s.i. per cycle.

Typically, to avoid entry of lubricants into the working volume of the machine, piston must operate dry in Stirling cycle engines. This requires that piston side loads from the crankcase must be eliminated. Elaborate, pre- 3,460,344 Patented Aug. 12, 1969 line else, and relatively large crankcase linkages are thus required. (US. Patent 3,077,732 Air Engine Improvement H. F. Reinhard et al., Feb. 19, 1963.) Unless a buffer chamber is used between the working pistons and the crankcase, the crankcase linkage must restrain the piston forces developed by the full internal pressure of the system working fluid plus the axial pressure variations producing useful work. This requires fairly massive construction in the crankcase linkage.

It is the purpose of this invention to provide mechanism which may be used to displace, compress or expand a gas working fluid. This mechanism when used in multiple unit combinations is particularly applicable to Stirling cycle engines of either the displacer or opposed chamber type. Double acting Stirling engines can be constructed employing a single cylinder. By eliminating reciprocating motion between the crankcase and the working chambers of the machine, the problem of sealing the working fluid from the crankcase is significantly reduced.

Further, internal pressure forces are balanced and the alignment of moving parts is not criticaly dependent on the crankcase linkage. The crankcase linkage experiences only those forces generated by output work, friction, and the inertia of oscillating mechanical components.

These and other objects of the invention Will be more readily apparent from the detailed description of the preferred embodiments when considered in conjunction with the accompanying drawings, in which:

FIGURE 1 is an elevation section view showing a characterizing component, according to the invention;

FIGURE 2 is a transverse section taken along the line 2-2 of FIGURE 1;

FIGURE 3 is a plan view, in section, taken along the line 33 of FIGURE 1 showing a connecting linkage detail;

FIGURES 4A through 4D are diagrammatic views showing a sequence of steps in the operation of a system, according to the invention;

FIGURES 5A and 5B are respectively diagrams showing the relationship between pressure and volume and be tween temperature and volume in ideal portions of the cycle of operation illustrated by FIGURES 4A through 4D;

FIGURE 6 is an elevation section view showing a system, according to the invention;

FIGURE 7 is a diagrammatic, exploded view with portions indicated as A through E corresponding to section lines 7A through 7B of FIGURE 6 respectively;

FIGURES 8A through 8D and diagrams of FIGURES 9A and 9B schematically and diagrammatically show another embodiment of a system, according to the invention;

FIGURES 10 and 11 respectively are an elevation section view and diagram similar to FIGURES 6 and 7, according to another embodiment of the invention;

FIGURES 12 and 13 are similar to FIGURES 10 and 11 showing yet another embodiment of the invention;

FIGURES 14A through 14D and diagrams shown in FIGURES 15A and 15B are similar to the views of FIG- URES 4 and 5 showing another embodiment, according to the invention;

FIGURES 16 and 17 likewise show another embodiment, according to the invention in the manner shown in FIGURES 6- and 7;

FIGURE 18 diagrammatically illustrates another system, according to the invention for controlling the speed of a shaft;

FIGURE 19 is a graph illustrating the relationship between pressure and volume within a system, according to that shown in FIGURE 18; and

FIGURE 20 is a diagrammatic illustration showing another embodiment of the system shown in FIG- URE 18.

Working fluid displacer and power unit subassembly A power unit subassembly to be employed includes two vanes 16, 17 keyed to an oscillating shaft 18 mounted within arcuate cylinder chambers 12 with a shaft 18 coaxially of the center line therebetween. Each chamber 12 is defined between the stationary portions or end walls 24, 26 and the radially outer side wall 20, the radially inner wall being formed by shaft 18. The side edges of the moving vanes 16, 17 are confined between and slidingly engage the top and bottom interior surfaces 13, 14 of chambers 12. Surfaces 13, 14 may be formed as a fixed portion of the chamber wall or be permitted to turn with shaft 18 as determined by design considerations. Shaft 18 is linked by a connecting rod 19 and cranks 21 to a crankshaft 22.

The four displacer volumes 23, 25, 27, 29 (as defined by vanes 16, 17, end walls 24, 26 and surfaces 13, 14) are in fluid communication with a working fluid or gas via ports 31, 32, 33, 34 each of which is associated with one of the volumes 23, 25, 27, 29 for supplying and exhausting fluid under pressure into and out of an associated one of the displacer volumes.

When a constant angular velocity is imposed on the external crankshaft 22, shaft 18 carrying vanes 16, 17 will oscillate back and forth with an angular velocity which varies harmonically through an angle which is preferably on the order of 110". Gas or working fluid will thus be displaced from two of volumes 23, 25, 27 and 29 and drawn into the other two volumes every half rotation of crankshaft 22, and with a volumetric flow rate which also varies harmonically. Subassembly 15 can be used to displace, compress and/or expand a gas working fluid.

Bushings 36, made of a relatively low friction material, such as carbon, are carried in bulkheads 37, 38. Bushings 36 prevent galling of shaft 18 as it oscillates in bulkheads 37, 38 and serve to maintain the concentricity of shaft 18 and vanes 16, 17. Some leakage of working fluid past bushings 36 into the inactive volumes 39, 41 will occur. The gas pressure in volumes 39, 41 will eventually stabilize at an equilibrium pressure substantially equal to the average pressure of the gas passing through the working volumes 23, 25, 27, 29; i.e., gas will leak into the inactive volumes 39, 41 from the high pressure working portions of the chambers 12, and gas will leak into the low pressure working portions of the chambers 12 from the inactive volumes.

As described further below, this pressure effect with respect to volumes 39, 41 will be utilized to control the actuating of a speed control system, and serves to simplify sealing the crankcase lubricant from the working fluid.

Seal 42, provided on shaft 18, serves to isolate the crankcase 43 from the gas in the inactive volume 41. Seal 42 comprises a ring 44 of suitable low coeflicient of friction material, such as Teflon, faced on its outer circumference with a rubber O-ring 46. Note that shaft 18 oscillates in the plane of seal 42 and therefore by the foregoing arrangement serves to eliminate pumping action as described above which might otherwise occur across seals in conventional reciprocating piston constructions between working and crankcase volumes.

As shown, the pressure in crankcase 43 has been equalized to the pressure of the inactive volume through line 47, connecting the crankcase 43 to the inactive volumes 39, 41. With this arrangement, there is virtually no pressure drop across seal 42 whatever. It is also possible to avoid pressurizing crankcase 43 by adding an appropriate thrust bearing to shaft 18 eliminating line 47 and by taking a pressure drop across seal 42.

With the crankshaft 22 rotating at a constant velocity,

shaft 18 oscillates harmonically through an angle of approximately Thus, the foregoing apparatus as described above, in brief, provides a displacer or power unit including means forming a cylinder containing a pair of chambers, an oscillating shaft coaxially disposed within the cylinder, and a pair of diammetrically disposed vanes carried by the shaft within the chambers. Each chamber is swept by an associated one of the vanes under oscillatory movement of the shaft. Finally, ports, on opposite sides of each vane, are disposed in fluid communication therewith.

Combinations of subassemblies 15 can be arranged in order to shuttle a gas working fluid back and forth through coolers, regenerators, and heaters of a type, for example, as employed in Stirling systems and in this manner thereby produce machines which will operate as Stirling cycle engines.

Displacer type Stirling cycle machine element FIGURE 4 diagrammatically represents four stages of operation of a displacer type Stirling cycle machine operating with a combination of subassemblies 15 of the above type. For the sake of clarity, only one vane of each pair is shown, and the motion of displacer vanes 61, 62 is schematically shown as completely independent of power vane 48 whereby one can be shown as stationary, while the other vane or vanes move. In FIGURE 4, vanes of subassembly 15-1 and 152 are fixed to the same shaft 49 and thus move together forming a displacer unit.

Volume 23a is connected to volume 2511 through three heat exchange components shown as a heating and cooling unit 51, 52 and a regenerator unit 53 interposed in the path between units 15-1 and '15-2.

Regenerator unit 53 serves to provide transitory storage and release of heat energy. Heating unit 51 serves to supply heat to the working fluid. Cooler unit 52 serves to abstract heat from the working fluid. As mentioned, regenerator unit 53 serves to provide transitory storage of heat as the working fluid is shuttled back and forth through the three units 51-53, Regenerator 53, typically, is a volume which is filled with a finely divided metallic material.

As shown in FIGURE 4, the working volume 54a of chamber 54 is also connected to coller unit 52. The volumes of all chambers are in free and open communication with each other, via lines 56, 57 and 58.

Thus, employing the basic components referred to immediately above, a Stirling cycle machine displacer assembly has been provided comprising the two volumes 23a and 25b which can each be varied from Zero to a predetermined value and which are each connected via the three heat exchangers 5153. In addition, a third chamber 54 contains a power volume 54a defined on one side of vane 48 so as to be varied from zero to some predetermined volumetric value. Volume 54a is further connected to the system as shown whereby the combination of the three volumes 23a, 25b and 54a along with the three heat exchangers 5153 serve to form a. Stirling cycle machine unit 59.

Referring to FIGURE 4A, it can be seen that volume 23a is at a maximum while volumes 25b and 54a are at a minimum. The working fluid is thus mainly in the hot end of machine unit 59 at maximum pressure and at minimum volume. (The hot and cold ends of the machine unit as referred to herein respectively refer to those portions of the machine unit next adjacent to heater unit 51 and cooling unit 52.)

The working fluid is allowed to expand from the condition shown in FIGURE 4A to FIGURE 48 by rotating vane 48 to the right. At such time, heat is aiso added to the working fluid from heater unit 51, Pressure is then reduced at constant volume from the condition shown in FIGURE 4B to that shown in FGURE 4C merely by rotating the vanes 61, 62 to the left. (By constant volume is meant the mere shuttling of gas from one chain her volume such as 23a to another chamber volume such as 25b via units 51-52.)

Thus, in shifting from the condition shown in FIG- URE 4B to that shown in FIGURE 4C, gas formerly in the diminishing volume 23a is shifted to the enlarging volume 251). During this step, heat is extracted from the working fluid and stored in regenerator unit 53. By extracting heat from the volume of working fluid, the pressure is thereby reduced.

Thus, in this condition, the working fluid is in the cold end of the Stirling cycle machine unit 59 and maintained at a minimum pressure and maximum volume by virtue of the condition of vanes 61, 62 and 48.

The working fluid is next compressed in shifting from the condition shown in FIGURE 4C to that of FIGURE 4D by rotating vane 48 to the left while heat is rejected to the cooler unit 52. Working fluid pressure is then increased at constant volume in shifting from the condition shown in FIGURE 4D to that shown in FIGURE 4A by rotating vanes 61, 62 to the right. During this step, heat is supplied to the working fluid from regenerator 53. Net work is produced from the cycle by the difference in work between the hot expansion and cold compression of the working fluid.

The schematic representations and conditions of the Stirling cycle machine unit 59 described above with reference to FIGURES 4A-4D is represented graphically at each of the four respective stages as noted in FIGURES 5A and 5B. In these figures, numerals 1, 2, 3 and 4 are associated with various positions of the graphical representation and serve to relate the schematic conditions of FIGURES 4A-4D to their respective graphical representation.

The compression and expansion strokes are a mixture of isothermal and isentropic processes and thus only approximate the ideal Stirling cycle. In a well designed machine over ninety percent of the working fluid temperature change occurs in regenerator unit 53 (as in steps 2 to 3 and steps 4 to 1) and thus, for practical purposes and clarity, the expansion and compression may be assumed to be isothermal.

The diagrams shown in FIGURES 5A and 5B are for purposes of explanation only and are obviously for an ideal cycle of an engine acting with discontinuous vane motion. In a practical machine, the four phases are merged, one into the other, to produce a smooth continuous envelope. This is accomplished by imposing harmonic motion on the displacer vanes and the power vanes and by synchronizing them to operate approximately 90 out of phase. 1

As is known, Stirling cycle machines can also be made to operate as either a refrigerator or a heat pump. If external work is supplied, and the power chamber lags the displacer chamber as shown in FIGURE 4, the cycle will reverse in direction and heat will be pumped up to the cooler unit 52 (acting as a heat sink) which refrigerates the heater end. If the power chamber is allowed to lead the displacer chamber, heat will be pumped from the cooler (heat source) to the heater end.

Referring to FIGURES 6 and 7, there has been arranged a machine unit comprising in combination heat exchange paths, wherein each path includes both a first heat exchange unit and a second heat exchange unit for adding or substracting heat energy to or from fluid in the path and a regenerator unit interposed in each of the heat exchange paths between the heating and cooling units. The regenerator serves to provide transitory storage and release of heat energy.

Still referring to FIGURES 6 and 7,.the machine unit there shown includes a displacer unit for shuttling working fluid between the two paths wherein the displacer unit includes means forming a pair of fluid chambers each divided into two volumes by a fluid displacement member movable within the chamber to respectively provide enlarging and diminishing volumes in each chamber. Means to support these members for movement back and forth in their respective chambers are provided whereby both members may conjointly compress or expand fluid in its associated chamber.

Both of the first heat exchange units are operatively coupled in free communication respectively with the enlarging and diminishing volumes of one of the chambers. Both of the second heat exchange units are operatively coupled in free communication respectively with the enlarging and diminishing volumes of the other of the chambers.

More particularly, and as now to be described in detail relative to FIGURES 6 and 7, the displacer unit for shuttling fluid is made up of two displacer subassemblies 63, 64 as described above relative to FIGURE 2 wherein a pair of moving vanes 66, 67 and 98, 99 are fixed to a common shaft 68. A power assembly 69, of a type similar to subassembly 15 (described above relative to FIGURE 2) is formed with movable vanes 71, 72 fixed to rotate with a hollow shaft 73.

As shown in FIGURE 6, the displacer construction is mounted in a cylinder structure 74 common to both subassemblies 63, 64 and formed with a common inner wall diameter for the vanes of both subassemblies 63 and 64-. In this arrangement, the displacer shaft 68 and power shaft 73 are mounted coaxially of each other whereby displacer shaft 68 passes through power shaft 73' and both shafts extend downwardly into crankcase 76.

Displacer shaft 68 and power shaft 73 are each connected to the same crankshaft 77 by means of the crank and connecting rod linkage comprised of crank arms 78, 79 and connecting links 81, 82 coupled to the ends of crank arms 83, 84.

It will be readily apparent that with crankshaft 77 rotating at a constant speed, a harmonic oscillating motion is imparted to displacer shaft 68 as well as to power shaft 73. This motion is synchronized between the two shafts, in a manner whereby one is on the order of out of phase with the other merely by adjusting the arcuate displacement between cranks 78, 79.

By making the connections shown in FIGURE 7 to the construction shown in FIGURE 6, it will be readily apparent that four of the Stirling cycle machine units 59 of a type as referred to with respect of FIGURE 4 are combined (FIGURE 6) in this single simple construction.

Thus, for purposes of correlating the construction and operation of unit 59 shown in FIGURE 4 and previously described with the combination of four Stirling cycle machine units shown in the system of FIGURE 7, it will be readily evident that one machine unit 59 in the condition shown in FIGURE 4B can be found in FIGURE 7. Accordingly, the diminishing volume 86a corresponds to the diminishing volume 23a of FIGURE 4A. Volume 86a (FIGURE 7) is coupled via line 87 along a heat exchange path through heater, regenerator, and cooler units 88, 89, 90, respectively, then via line 91 (corresponding to line 57 in FIGURE 4B), and thence via line 92 (corresponding to line 57 in FIGURE 43) to the enlarging volume 93a of displacer subassembly 64. In addition, line 91 further leads to the enlarged volume 94a of power assemblies 69, which enlarged volume corresponds to volume 5411 of FIGURE 4B.

Similarly, having traced one such Stirling cycle machine unit of a type such as 59 shown in FIGURE 4 and correlating its construction with the construction shown in FIGURE 7, it Will be readily apparent that three additional such Stirling cycle machine units are therein embodied which may be readily provided in the simple structure shown in FIGURE 6.

It is to be noted, however, that while FIGURE 6 shows schematically only two heat exchange paths employing the heat exchange units, the additional two heat exchange paths of the FIGURE 7 system are readily provided but for sake of clarity, have not been shown in FIGURE 6.

From inspection of FIGURES 6 and 7, it will be readily apparent that the four basic Stirling cycle units 59 as described in FIGURE 4 are arranged in pairs with the enlarging and diminishing volumes of each Stirling cycle machine unit disposed in a manner whereby the two units of each pair of units is passing through the same cycle stage at the same time and therefore the pressure in the opposite chambers of each subassembly 63, 64 as well as of 69 is the same.

The projected area across shaft 68 in each chamber, for example, as swept by vanes 66, 67 is equal to the projected area in the opposite chamber. The working fluid pressure is equal in opposite chamber volumes of each subassembly and therefore there is no unbalanced side load exerted upon shaft 68 or upon shaft 73. Thus, side loads are eliminated in the displacer shaft assembly and in the power assembly shaft by balancing of forces.

In order to insure that pressure will be the same in opposite volumes of the opposite chambers of each subassembly, and between subassemblies, two balancing lines 95, 96 may be installed in the external piping, or each pair of machine units 59 (FIGURE 4) may operate through a common heat exchange path. By eliminating side loads on the displacer shaft, the need for a shaft bearing at the hot end is eliminated.

Because gas pressure side loads on shaft 68 have been eliminated, dry guide bushings 97, made of a suitable material, such as carbon, can be incorporated on shaft 68 to positively prevent the shaft from whipping. This will permit a close clearance to be maintained between the vanes and the slidingly engaged walls of each chamber so as to minimize internal leakage of working fluid between the enlarging and diminishing volumes of each chamber.

As shown in FIGURES 6 and 7, gas pressure forces act on displacer vanes 66, 67 and 98, 99 to create couples to generate a torque in shaft 68 and in the wall of cylinder 74. The couples in one displacer subassembly 63 are opposed and balanced by the couples in the other displacer subassembly 64 through the torque in shaft 68 as well as in that portion of the wall of cylinder 74 extending between the two su-bassemblies 63, 64. The only work or torque required to oscillate shaft 68 and thus transfer gas or working fluid back and forth between the hot and cold volumes of the displacer subassemblies is that which is required to overcome frictional pressure drop in the external heat exchange paths defined by heat exchangers such as 88, 89, 90.

The two arcuate chambers of power assembly 69 swept by vanes 71, 72 serve to define four volumes 94a, 94b, 94c, 94d. Two volumes thereof expand high pressure working fluid and two volumes com ress low pressure working fluid during each half revolution of crankshaft 77. This machine, thus, is double acting.

The net pressure across the moving vanes 71, 72 creates couples which generate a torque in the hollow power shaft 73.

Power vanes 71, 72 lag displacer vanes 66, 67 and 98, 99 by approximately 90 for heat engine and refrigeration applications. By reversing the direction of rotation of output shaft 73, power vanes 71, 72 can be made to lead the displacer vanes by approximately 90 for heat pump applications.

A pressure balancing line 101 between crankcase 76 and the inactive volumes 102, 103, 105 defined around the working chambers of power assembly 69 and displacer assembly 63, 64 is shown. Pressure in crankcase 76 is thus equalized at that mean system pressure which exists in inactive volumes 102, 103, 105 by line 101 which will eliminate all axial thrust on displacer shaft 68 and power shaft 73. This will also serve to eliminate pressure drop across the shaft seals 104, 106.

From the foregoing, it will be readily apparent that a Stirling cycle engine according to the above construction features the following advantages:

The machine is double acting so as to enhance power density. A single cylinder incorporates four displacer volumes and four power volumes in a manner producing a balanced double acting arrangement.

From the compact arrangement of the machine (FIG URE 6) it can be seen that the length of interconnecting ducts between chambers is very short. This reduces dead volume and further enhances power denesity as compared with multicylinder double acting piston machines.

(Where it is desired not to pressurize crankcase 76, thrust bearings may be added on shafts 68 and 73. By eliminating line 101, a steady pressure drop will then exist across the shaft seals 104, 106.)

Pressure variations in the machine which occur between the expansion and compression stroke create forces which act concentrically of both shafts 68 and 73. All axial forces created by cycle pressure variations are balanced internally at each subassembly by the chamber surface slidingly engaging the edges of the vanes. The seals between crankcase 76 and the working fluid chambers are therefore not subjected to pressure variations during each cycle as in reciprocating piston machines. The shaft seals are exposed to a steady mean system pressure found in the inactive volumes.

Shafts 68 and 73 oscillate in the plane of seals 104 and 106 and therefore no mechanical pumping action occurs as occurs with reciprocating piston rods.

In active volumes outside the working chambers will come to an average equilibrium pressure level defined between the peak expansion stroke pressure and minimum compression stroke pressure of the working cycle. Venting these inactive volumes to the crankcase through an oil trap 107 (FIGURE 6) eliminates all axial thrust on the power shaft and displacer shaft and eliminates the pressure drop across the shaft seals. This arrangement serves to further reduce the severity of the problem of sealing the crankcase lubricant from the active working fluid of the machine.

The linkage of the power chamber to the crankshaft will only experience forces generated by the output work, work required to overcome internal machine friction, and the inertia forces generated by the oscillating mechanical components. Reduced loading on the crankcase components as well as the geometry of the machine construction leads to a significantly lighter and more compact crankcase as compared to machines which employ reciprocating pistons.

According to another embodiment (FIGURES 8 and 9) of the invention, and with reference to FIGURE 8, there is shown diagrammatically the four stages of operation of another displacer type Stirling cycle machine unit operating with a combination of subassemblies of a type as disclosed in FIGURE 1. For the sake of clarity, only one chamber of each mechanism is shown and the motion of the vanes is shown as completely independent of each other so that one may be considered to be stationary while the other moves.

Referring to FIGURE 8, a displacer vane 108 sweeps an arcuate portion of a displacer cylinder and serves to define a chamber 109 as the pair of alternately diminishing and increasing volumes 111, 112. Volumes 111, 112 are respectively coupled to the opposite ends of a heat exchange path 113 of the type referred to above. Thus, the heater unit serves to supply heat to the working fluid, a regenerator unit serves to store and reutrn heat to the working fiuid as it shuttles back and forth from volume 111 to volume 112 vice versa, and the cooler unit serves to extract heat from the working fluid as it passes therethrough.

In the power assembly 114, a vane 116 sweeps through a chamber 117 so as to define enlarging and diminishing volumes 118, 119 on opposite sides of vane 116. Volume 118 is in the cold end of heat exchange path 113, as all the volumes are in free and open communication with each other, albeit through heat exchange path 113.

It is to be noted that volume 111 is separated from volume 112 only by the single vane 108. The only gas pressure forces generated across vane 108 are those which are developed by the working fluid frictional pressure drop in the external heat exchange path 113 during vane movement. The subassembly 110 therefore serves to form the displacer unit, and power assembly 114 forms the working unit of a Stirling cycle machine. This combination of interconnected volumes together with the heat exchange path 113 accordingly therefore defines a further embodiment and simplification of a Stirling cycle machine unit 121.

Each of the four phases of operation of the Stirling machine unit 121 described in FIGURES 8A through 8D respectively are represented as the four steps labeled 1 through 4 noted in the graphs of FIGURES 9A and 9B.

Thus, at point 1, volume 111, coupled to the hot end of heat exchange path 113, is at its maximum and volumes 112, 118 are at a minimum. The working fluid is thus in the hot end of the machine unit at maximum pressure and minimum volume. The working fluid is allowed to expand from point 1 to point 2 by rotating vane 116 in chamber 117 and heat is added to the working fluid by the heater unit of heat exchange path 113.

Pressure is next reduced by shuttling the working fluid at constant Volume by oscillating the vane 108 so as to diminish volume 111 and enlarge volume 112. In this step, heat is extracted from the working fluid and stored in the regenerator unit of heat exchange path 113. The working fluid is then compressed in the next step as then traced from point 3 to point 4 by rotating vane 116 in chamber 117 to the left and at the same time heat is rejected to the cooler unit of path 113.

Working fluid pressure is next increased at constant volume from point 4 to point 1 by rotating vane 108 to the right. In this step, heat is supplied to the working fluid from the regenerator, and the heater as it shuttles through the heat exchange path 113.

It should be noted that in this machine that both the hot and cold working fluid will be exposed to the same cylinder wall of subassembly 110 for each complete cycle of operation of the machine. This does not materially affect the performance of the machine because the heat transfer rate between the cylinder walls and the working fluid is significantly lower than the heat transfer rate in the external heat exchangers of path 113.

The average velocity of gas in the changing volumes of the displacer subassembly 110 is significantly lower than the average velocity of gas passing through path 113. The film coefiicient at the walls of the displacer chamber 109 is therefore significantly lower than the film coefficient in the exchangers 113. It is calculated that, typically, a reduction of approximately three percent in overall thermodynamic efiiciency results from introducing this additional heat leakage path in the machine.

A beneficial effect which results from this arrangement, however, is that the displacer chamber walls and associated mechanical components operate at a lower temperature due to being cooled by the working fluid. Less expensive materials can thus be utilized to fabricate a machine unit by taking advantage of this reduction in the severe service temperatures or, on the other hand, this Stirling cycle machine unit can be subjected to operate at higher temperatures than heretofore, as limited only by material strength and the temperature considerations.

The diagrams as shown in FIGURES 9A and 98, as with diagrams of FIGURES A and 5B are for the ideal cycle of an engine acting with theoretically discontinuous vane motion. In a practical machine, of course, the four phases are merged one into the other in order to produce a smooth continuous envelope. This is accomplished by imposing harmonic motion on the displacer vanes and the power vanes and making them operate approximately 90 out of phase.

As mentioned above with respect to the Stirling machine unit 59, Stirling machine unit 121 can also be made to operate either as a refrigerator or heat pump.

According to another embodiment, the foregoing Stirling cycle machine unit 121 has been embodied in the construction shown in FIGURES 10 and 11. The arrangement of displacer assembly, power assembly, crankcase, pressure balancing line and pressure balanced shaft seals is similar to the machine unit shown in FIGURES 6 and 7. The arrangement as shown in FIGURES 10 and 11, however, takes advantage of the foregoing structure to employ a rearrangement of the units of the heat exchange paths so as to provide a number of additional advantages.

Accordingly, due to the similarity in construction between the embodiment shown in FIGURES 10 and 11 and the embodiment shown in FIGURES 6 and 7, comparable elements appearing in FIGURES 10 and 11 and previously described relative to the embodiment of FIG- URES 6 and 7 have been referred to by reference numbers including a third significant digit employing the numeral 2. Thus, in FIGURE 6, shaft 68 corresponds to shaft 268 in FIGURE 10.

Accordingly, the construction shown in FIGURE 10 entails all of the advantages of the prior described embodiments in addition to having a number of advantages unique to itself.

Thus, the low pressure drop across the shuttling vanes of each displacer unit will reduce the internal gas leakage problem in the machine. Costs are reduced by making mechanical clearance problems considerably less critical. Further, a less massive construction is made possible by the lightly loaded transfer vane assembly which reduces inertia loading in the displacer shaft assembly and connecting rod linkage. In addition, benefits are gained from cooling the displacer unit with the working fluid as described above.

While the foregoing embodiments have related to a double acting arrangement, it is also possible to construct a single acting machine utilizing the operating sequence described in FIGURE 8, but using only two basic Stirling cycle machine units. A construction according to this embodiment has been shown in FIGURES 12 and 13. The displacer shaft 126 is coupled to the oscillating vanes 127, 128 of a single subassembly 129. A power subassembly 131 is coupled to a shaft 132 whereby linkages contained in crankcase 133 may be operated as above described.

In the system shown in FIGURE 13, it will be noted that displacer assembly 129 is ported to only two of the changing volumes of power assembly 131, namely to volume 134 and volume 136. The other two changing volumes 137, 138 of chambers 139, 140 respectively are ported to a buffer chamber 141 maintained at the mean system pressure.

The vanes in power chambers 139, 140 are driven by working fluid pressure during the expansion stroke and by pressure of buffer chamber 141 during the compression stroke. Buffer chamber 141 takes the place of a flywheel and prevents working fluid leakage from the system. This machine is thus single acting, that is to say cycle expansion and compression requires one full revolution of crankshaft 142.

The buffer chamber is a volume which when connected to the system as shown in FIGURE 13 will contain working fluid at the average cycle pressure, i.e., leakage past the power vanes will balance (into and out of the buffer chamber volume) over an expansion and compression stroke. The buffer chamber volume is made large relative to the power volume so that the pressure fluctuation in the buffer chamber due to volume change is small over a complete cycle. Note FIGURE 19 for the relationship between buffer chamber pressure (same as inactive volume pressure) and cycle pressure.

According to another embodiment as shown in FIG- URE 14, and characterized by its opposed volumes, the basic components of a Stirling cycle machine comprise the two volumes 146, 147 which are in free communication with one another via the three heat exchange units forming heat exchange path 148. Volume 146, 147 are at different temperatures due to their relationship with the units of path 148 and each may be varied from a volumetric capacity of zero to some predetermined value.

The four stages of operation of the unit shown in FIG- URE 14 are represented in FIGURE 14A through 14D. Movement of vane 149 is opposed by movement of vane 151 through an external linkage (not shown) but represented by the phantom line 152. In the description of the sequence of steps in the operation of this machine unit, it is to be understood that both vanes move simultaneously rather than each being represented as independent of the other.

The operative steps of the cycle of operation are, as in the preceding graphs, referred to in the numerical sequence of the FIGURES 14A through 14D as represented by the numbers 1 through 4.

Thus, at point 1 in FIGURES 15A and 15B, it can be seen that most of the working fluid is located in the hot chamber 146 and between both chambers it is at a minimum volume. The working fluid is thus at maximum pres sure and minimum volume. The working fluid is then allowed to expand from point 1 to point 2 by moving the vanes 149, 151 as indicated in FIGURE 14B while heat is added to the working fluid from the heater unit of heat exchange path 148. It is to be noted that this expansion occurs with most of the working fluid in the hot end of the machine.

Pressure is next reduced at constant volume (from point 2 to point 3) by rotating both vanes 149, 151 to the right through equal arcs by suitable linkage 152. In this step, heat is extracted from the working fluid and is stored in the regenerator unit of heat exchange path 148.

The working fluid is compressed in the next step from point 3 to point 4 by moving vanes 149, 151 as indicated and heat is then removed from the working fluid by the cooler unit. Note that this compression occurs with most of the working fluid in the cold end of the machine.

Working fluid pressure is next increased at constant volume from point 4 to point 1, by rotating both vanes to the left through equal arcs as noted between FIGURES 14D and 14A. In this step, heat is re-supplied to the working fluid from the regenerator unit of heat exchange path 148.

The movement of vanes described above is schematically shown as discontinuous with both vanes 149 and 151 moving simultaneously through the discrete steps described in FIGURES 14A through 14D. The diagrams as shown in FIGURES 15A and 15B are for the ideal cycle of an engine acting with theoretically discontinuous vane motion. In an actual embodiment, the four phases merge one into the next in order to produce a smooth continuous envelope.

This is accomplished by imposing harmonic motion on each vane and making them operate about 90 out of phase with each other. Note that in this arrangement both vanes 149 and 151 act simultaneously to perform a power function (expansion, compression) and displacer function (constant volume heat addition or removal).

Net work is produced from the above cycle operation by the difference in work between the hot expansion and cold compression of the working fluid.

The compression and expansion strokes are a mixture of isothermal and isentropic processes and, thus, only approximate the theoretically ideal Stirling cycle. In a well designed machine, however, over ninety percent of the working fluid temperature change occurs in the regenerator unit of heat exchange path 148 and, thus, for practical purposes, expansion and compression may be assumed to be substantially isothermal.

A structural embodiment of the arrangement shown in FIGURE 14 has been provided as shown in FIGURES 16 and 17.

Thus, referring to FIGURE 17, it will be apparent that the hot end of the machine as comprised by the heat exchange units 153, 154, 156, 157 are adjacent the changing volumes defined in eachof chambers 158, 159 of subassembly 161. The cold end of the machine (as characterized by the heat exchange cooler units 162-165) is disposed nearest the changing volumes defined in chambers 166, 167 of power subassembly 168. Shaft 169, on which the hot end vanes 171, 172 have been mounted is disposed coaxially within shaft 173 on which the cold end vanes 175, 180 are carried. Shaft 169 and shaft 173 both extend downwardly into the crankcase 184 of the machine.

The shafts 169, 173 are connected to the crank and connecting rod linkage shown in FIGURES 16 and 17 in order to operate crankshaft 174 at constant speed while imparting harmonic oscillating motion on both shafts 169, 173. This movement is synchronized between shafts 169, 173 in a manner to operate them on the order of out of phase. In this manner, the movement of vanes 149, 151 of FIGURE 14 is achieved.

Each of the four changing volumes of chambers 158, 159 in the hot" end of the machine is connected to a changing volume in chambers 166, 167 in the cold end of the machine via a heat exchange path comprised of one of the heater units 153, 154, 156, 157, one of the regenerator units 176-179, and one of cooler units 162- 165. It can thus be seen that four basic Stirling cycle machine units of a type as described with respect to FIGURE 14 have been combined in a single simple machine shown in FIGURE 16.

Opposite volumes in the hot end subassembly 161 and opposite volumes in the cold" end subassembly 168 are maintained at the same pressure since they execute the same cycle stages simultaneously and in this manner the Stirling cycle units balance each other. Again, it should be readily apparent from the symmetry of the machine that there is no unbalanced force across either shaft. All pressure forces acting on the shafts are exerted as pure couples through the vanes. Two pressure balancing lines 181, 182 serve to insure equal pressure in each pair of Stirling cycle units, or each pair of units may operate through a heat exchange path common to each (not shown).

Each pair of Stirling cycle units is out of phase in the cycle by wth the other. Thus, one pair of Stirling cycle units is in compression while the other pair is in an expansion state or condition. Accordingly, the machine is double acting.

The cold end chambers lag the hot end chambers by approximately 90 for heat engine and refrigeration applications, and by reversing the direction of rotation of the crankshaft the cold end chambers can be made to lead the hot end chambers approximately 90 for heat pump applications.

A pressure balancing line 183 between crankcase 184 and the inactive volumes 186, 187 serves to equalize the crankcase pressure to the mean system pressure existing in these inactive volumes so as to eliminate all axial thrust on the working chamber shafts and also to eliminate pressure drop across the shaft seals 189, 191.

This opposed chamber machine arrangement incorpo rates all of the advantages ascribed to the displacer type machine defined by FIGURES 4, 5, -6 and 7, i.e., double acting, compact layout to minimize dead volume, crankcase seal with no pumping action or pressure drop, and a compact crankcase as compared with reciprocating piston machines. In addition, however, only two subassemblies 161, 168 are required to produce a double acting machine where three such subassemblies are required in the double acting displacer type machines described above (FIG- URES 6, 7 and 10, 11).

Each changing volume in this arrangement (FIGURES 16, 17) performs a power and a displacer function. Thus, there are eight power volumes in this opposed volume arrangement as compared with four power volumes in the double acting displacer type machines described earlier above.

Detailed analysis of the embodiment shown in FIG- URES 16, 17 indicates that machine power density is typically enhanced by a factor on the order of 1.75 when compared to the double acting displacer machines of FIG- URES 6, 7 and 10, 11. This arrangement (FIGURES l6 and 17) provides higher power density in a highly simplifled construction. It is not necessary that the cold volumes equal the hot volumes.

A method for regulating the speed of the Stirling cycle engine responsive to changing system pressures can be readily eifected employing the constructions above in order to accommodate varying loads.

As is generally known, it is desirable to be able to regulate power level and/ or speed of the machine without removing working fluid from the system. A particularly desirable performance is derived from Stirling cycle machines when the working fluid is either hydrogen or helium and it is impractical to merely discharge these gases out of the system in order to reduce the load. Pumping these gases in and out of storage containers as load conditions vary is also undesirable due to the necessity of employing auxiliary equipment and due to the power requirements involved for such pumping.

A method of regulating power and/or speed responsive to changes in system pressure, as now to be described, does not require removal of any working fluid from the machine nor does it require the utilization of auxiliary power sources. Further, the thermodynamic efliciency of the machine remains the same at partial loads.

It is believed known that in order to maximize power density, the dead volume in a Stirling cycle machine or any positive displacement machine must be minimized. Dead volume is that volume, such as external heat exchangers and ducts, which will not be swept by the dis placer or power pistons. In conventional machines, the dead volume is approximately equal to one-half of the swept volume of the expansion space. Doubling the dead volume will reduce power density by a factor of about two. Thermal efliciency remains substantially constant, as reported in the Journal of Mechanics Engineering Science, volume 4, No. 3, 1962, in an article by Mr. G. Walker.

According to the method now to be described, advantage is taken of this dead volume effect and varying system pressure in order to regulate speed and/or power level merely by varying the dead volume. A means by which this is to be accomplished is shown in FIGURE 18. A chamber 192 within which is contained a variable volume is connected to the heat exchanger ducts 193 leading to a Stirling cycle engine (not shown). Ducts 193 represent dead volume. Chamber 192 contains a flexible diaphragm 194 exposed to active system working fluid pressure on one side and oil on the other. An oil reservoir 195 is shown which is pressurized by gas from the inactive volume of the machine.

Inactive volume of the machine is made up of those volumes in the main cylinder which are adjacent the working chambers as previously described. (In the foregoing described constructions, the inactive volumes, for exam ple, have been shown as vented to the crankcase.)

Pressure in the inactive volumes stabilizes at the mean average cycle pressure. Leakage of gas working fluid will escape from the working chambers into the inactive volumes during the high pressure portion of the cycle and gas will leak from the inactive volumes back into the working chambers during the low pressure portion of the cycle. In double acting machines, gas will constantly leak into and out of the inactive volume.

Because of the close clearance of the leakage paths, the leakage rate into and out of the inactive volumes is very low and the pressure in inactive volumes remains substantially constant. Inactive volume pressure therefore stabilizes at the mean average cycle pressure because the leakage rates in and out of the active system must be equal.

The relationship between inactive volume pressure and active cycle pressure is shown in FIGURE 19. Thus, the peak cycle pressure can run about 2000 p.s.i. and the minimum cycle pressure can run approximately 1000 p.s.i. with a mean pressure (i.e., as in the inactive volumes) of 1500 p.s.i.

Variations in active cycle pressure above and below the inactive volume pressure (maintained in oil reservoir are used to move oil to expand or contract flexible diaphragm 194 and thus vary the dead volume in the machine. The movement of oil into and out of the diaphragm-defined volume of container 196 is controlled by flow control means including a two-way valve 197 and a pair of check valves 198, 199. Valve 197 is of a type which can either be closed or operated to complete the circuit between oil reservoir 195 and either of check valves 198, 199. The direction of oil flow (into or out of container 196) is controlled by the check valves.

Valve 197 can be actuated manually or through an appropriate speed sensing or load sensing device as indicated at 200 shown schematically as operatively responsive to sense movements of a power shaft 201 and responsive to change therein for operation of a suitable control 202. Control 202 conditions valve 197 so as to connect reservoir 195 via one or the other of valves 198, 199.

As shown in FIGURE 18, the check valves 198, 199 will only permit a flow of oil in the direction indicated by their respective arrows. If the machine slows down, as sensed by speed sensing device 200, thereby indicating that more power is required to maintain speed, the twoway valve 197 is actuated in order to complete the hydraulic circuit through check valve 199. Oil will then flow to container 196 so as to expand diaphragm 194 during that portion of the cycle when the inactive volume pressure detected via reservoir 195 is greater than the cycle working fluid pressure detected via duct 193. The overall system dead volume is thereby reduced, machine power density is increased, and its speed is also increased.

To maintain speed, under steady state load conditions, the two-way valve 197 is closed since the proper dead volume has thereby been established.

In order to reduce speed, valve 197 is actuated in a manner to complete the hydraulic circuit through check valve 198. Oil then flows out of container 196 during that portion of the cycle when the cycle pressure (acting on diaphragm 194) is greater than the inactive volume pressure (acting on reservoir 195). The condition of valve 197 prevents oil from flowing into container 196 via check valve 199 during that portion of the cycle when the cycle pressure is lower than the inactive volume pressure, whereas valves 198, 197 freely discharge oil to relieve diaphragm 194 when cycle pressure exceeds the inactive volume pressure. The inactive or dead volume is thus increased, machine power density reduced, and machine speed is accordingly reduced.

Thus, in a general manner and for use with an engine system of a type wherein the pressure of a working fluid in the active portions of the engine system fluctuates above and below a mean pressure and wherein other inactive portions of the system remain stabilized at substantially the mean pressure notwithstanding the above fluctuations, a speed regulating arrangement as above described generally comprises means defining a first and second expansible fluid volume to respectively alternately enlarge and diminish so as to respectively accept and discharge fluid, such as in the opposite ends of a cylinder. The first fluid volume is coupled to the active portions of the system so as to respond to the pressures thereof, while a reservoir of fluid is provided in fluid communication with the inactive portions of the system so as to be subject to the mean system pressure thereof. Finally, fio'w control means are arranged for passing fluid from the reservoir into and out of the second fluid volume so as to respectively decrease or increase the active volume of the engine system by increasing or decreasing the first volume in response to changes in the second volume. The fluid is passed into and out of the second volume under transitory pressure diiferentials existing between the pressure of the inatcive portions and the active portions of the engine system.

By making the connections now to be described with reference to FIGURE 20, the foregoing system for speed regulation can be adapted to any Stirling cycle engine. Thus, there is furher included means creating an artificial inactive volume (where one does not already exist in the machine). Rather than make the direct connection via line 204, a fluid storage, such as the plenum chamber 203, is interposed and fluid coupled via a flow restricting impedance, such as the capillary tube 191 (or orifice) to the active cycle working fluid volume whereby reservoir 195 is pressurized via means serving to smooth out the system pressure fluctuations and thereby form a rela tively constant fluid pressure source. Plenum chamber 203 could, of course, be a portion of reservoir 195.

The pressure in chamber 203 will stabilize at the system mean pressure. Thus, flow of gas into the volume of chamber 203 occurs while cycle pressure is greater than the pressure within chamber 203. Flow of gas out of chamber 203 occurs when cycle pressure is less than that within chamber 203. Pressure in the inactive volume of chamber 203 stabilizes when gas flow in equals gas flow out. Inasmuch as the pressure drop through restrictive capillary 191 is fixed, the inactive volume pressure within chamber 203 must stabilize at the average cycle pressure.

Thus, capillary 191 severely limits the gas flow rate into and out of the inactive volume chamber 203 and thereby isolates chamber 203 from sharp pressure variations in the cycle. Chamber 203, therefore, does not add to the overall dead volume of the machine.

What is claimed is:

1. In apparatus of the kind described an engine unit comprising means forming a first arcuate chamber, means forming a second arcuate chamber, means in each of said chambers movable between advanced and retracted positions to form in each chamber a pair of alternately enlarging and diminshing volumes each adapted to receive and discharge a working fluid, oscillating means coupled to move with the movement of the last said means associated with each of said chambers, means forming a flow passage in fluid communication with each of said volumes and means forming a fluid path in open communication between an enlarged one of said volumes and a diminishing one of said volumes, said fluid path including heat exchange means.

2. Apparatus according to claim 1 wherein said heat exchange means includes a heater and a cooler unit and a regenerator therebetween.

3. In apparatus of the kind described an engine unit comprising means forming a first arcuate chamber, means forming a second arcuate chamber, fluid. displacer means in each of said chambers movable between advanced and retracted positions to form in each chamber a pair of alternately enlarging and diminishing volumes each aretracted positions to form in each chamber a pair of alternately enlarging and diminishing volumes each adapted to receive and discharge a working fluid, oscillating means forming a flow passage in fluid communication with each of said volumes, and means forming a pair of fluid paths, each in open communication between an enlarging one of said volumes and a diminishing one of said volumes, and means serving to drive said oscillating means to move said displacer means harmonically between said advanced and retracted positions.

4. Apparatus according to claim 3 wherein the respective displacer means of said chambers form a couple in a common direction about an axis of rotation therebetween.

5. In apparatus of the kind described, a hot gas engine unit including a housing, a pair of arcuate chambers defined within the housing, fluid displacer means within each chamber movable between advanced and retracted positions to form in each chamber a pair of alternately enlarging and diminishing volumes each adapted to receive and discharge a working fluid, the movements of said fluid displacer means in one chamber being disposed substantially out of phase with respect to the movements of the fluid displacer means in the other chamber, means forming a flow passage in fluid communication with each of said volumes, and oscillating shaft means coupled to be moved with conjoint movement of both said fluid displacer means.

6. For use in a hot gas engine of a type having first and second heat exchange paths each comprised of heating and cooling units for respectively adding or subtracting heat energy to or from fluid in the paths and a regenerator unit interposed between the heating and cooling units in each path for transistory storage and release of heat energy, a fluid handling unit comprising means forming a housing, means serving to subdivide said housing into a pair of arcuate chambers, an oscillating shaft coaxially disposed between said chambers, a pair of diametrically disposed vanes oscillated by said shaft, each chamber being swept by an associated one of said vanes under oscillatory movement of said shaft, and ports in said chambers on opposite sides of each vane in fluid communication therewith.

7. In a hot gas engine machine, apparatus comprising, in combination, heat exchange paths, each path including both a first heat exchange unit and a second heat exchange unit for adding or subtracting heat energy to or from fluid in said path and a regenerator unit interposed in each path between said heating and cooling units for transitory storage and release of heat energy, a displacer unit for shuttling fluid between said paths, said displacer unit including means forming a pair of arcuate fluid chambers, a pair of fluid displacement members respectively movable within said chambers to respectively form enlarging and diminishing volumes in each chamber, means serving to support said members for oscillating movement back and forth in their respective chambers for both members to conjointly diminish and enlarge fluid volume in each associated chamber, both said first heat exchange units being operatively coupled in free communication with the enlarging and diminishing volumes respectively of one of said chambers, and both said second heat exchange units being operatively coupled in free communication with the enlarging and diminishing volumes respectively of the other of said chambers.

8. In a hot gas engine machine comprising, in combination, first and second pairs of heat exchange paths, each path including heat exchange means forming both a heating unit and cooling unit for respectively adding or subtracting heat energy to or from fluid in said path and a regenerator unit interposed in each path between said heating and cooling units for transitory storage and release of heat energy, a combined power-displacer unit for moving fluid between said paths, said unit including means forming a pair of arcuate fluid chambers, a pair of fluid displacement members respectively movable within said chambers to respectively form enlarging and diminishing volumes in each chamber, shaft means serving to support said members for movement back and forth in their respective chambers, each member being disposed with respect to its chamber to conjointly discharge and conjointly accept rfluid in its chamber, another combined power-displacer unit comprising means forming a pair of arcuate fluid power chambers and a pair of fluid displacement members diametrically disposed of said shaft means and respectively movable within the last named said chambers, each of said last named chambers further including fluid passage means operatively coupled to said paths for supplying and exhausting fluid into and out of 17 both said last named chambers, said shaft means serving to form a driving connection coupled to move the displacer members of both said units harmonically to provide a volumetric displacement in said chambers maintained in a predetermined phase relationship.

9. In a hot gas engine, a working fluid displacer assembly comprising a housing, a pair of displacer units within said housing, each unit including a right cylindrical portion of said housing forming a pair of arcuate chambers, said portions being substantially of a common diameter, fluid displacer means within each chamber movable between advanced and retracted positions about an axis of rotation to form in each chamber a pair of alternately enlarging and diminishing volumes each volume being adapted to receive and discharge working fluid, the movements of said fluid displacer means in one chamber being disposed to form a couple in a common direction of rotation about an axis of rotation with respect to another of said chambers, oscillating means common to both units and coupled to be moved with conjoint movement of said displacer means of said units, means serving to move said oscillating means harmonically back and forth through a predetermined arc, and means forming a flow passage in fluid communication with each of said volumes for passing fluid into and out of said volumes.

10. Apparatus according to claim 9 further including means forming fluid path connections, each path being in free communication between an enlarging volume in one unit and a diminishing volume in the other unit, each said path including heat exchange means including heater means, cooler means, and regenerator means therebetween, the enlarging volumes in one unit being connected to the heater means of a first and a third fluid path, the diminishing volumes in said one unit being connected to the heater means in a second and fourth fluid path, the diminishing volumes in the other unit being respectively connected to the cooler means in said first and third fluid paths and the enlarging volumes in said other unit being connected respectively to the cooler means in said second and fourth fluid paths for displacing, raising or lowering the pressure in the working fiuid of the hot gas engine.

11. In apparatus of the kind described, a hot gas engine displacer unit comprising a housing, a pair of arcuate chambers defined within the housing, fluid displacer means within each chamber movable between advanced and retracted positions to form in each chamher a pair of alternately enlarging and diminishing volumes each adapted to receive and discharge a working fluid, the movements of said displacer means in one chamber forming a couple in a common direction of rotation about an axis with respect to the movements of the fluid displacer means in another chamber, oscillating shaft means coupled to be moved with conjoint movement of both said fluid displacer means, means serving to oscillate said shaft means harmonically back and forth through a predetermined arc, means forming flow passages in fluid communication with said volumes, means forming fluid path connections in free communication respectively between first and second diminishing volumes, said fluid path connections each including a heater, a regenerator, and a cooler unit, the heaters being connected to the enlarging volumes and the coolers being connected to the diminishing volumes.

12. Apparatus according to claim 11 further including a power unit comprising fluid displacement means operably coupled to said oscillating shaft means and movable between advanced and retracted positions in a housing to form a pair of enlarging arcuate fluid volumes and a pair of diminishing fluid volumes, means forming a buffer chamber adapted to be fluid pressurized to the mean pressure of the working fluid of the system, fluid connections forming flow paths in fluid communication between a first like pair of said power volumes and said buffer chamber and a second like pair of said power 18 volumes and respective ones of said cooler units, said shaft means serving to form a driving connection coupled to move the displacer means of both said units harmonically to provide a volumetric displacement in said chambers maintained in a predetermined phase relation.

13. In a hot gas engine the combination comprising means forming a housing, a pair of fluid displacer units in the housing, each said unit including a pair of arcuate chambers, a fluid displacement member respectively in each chamber and movable therein to form enlarging and diminishing volumes in its associated chamber, oscillating drive means common to both said units and coupled to be moved with movement of said displacement members of the units, means forming fluid flow paths respectively extending, in free communication, between an enlarging pair of volumes of one of said units and a diminishing pair of volumes in the other of said units, each said path including a heater, a cooler, and a regenerator therebetween, the enlarging volumes of one of said displacer units being respectively coupled to the heater of the fluid flow path associated therewith, and means forming fluid flow paths respectively extending, in free communication, between a diminishing pair of volumes of said one of said displacerunits and an enlarging pair of volumes of said other displacer unit, each of the last named flow paths including a heater, a cooler and a regenerator therebetween, the diminishing volumes of said one of said displacer units being respectively coupled to the heater of the fluid flow path associated therewith, the diminishing and enlarging volumes of said other displacer unit being coupled to a respective one of said coolers, means serving to move said drive means harmonically back and forth to transfer fluid between said displacer units to lower and raise the pressure of the fluid alternately in each fluid path by heating and cooling said fluid.

14. Hot gas engine apparatus according to claim 13 further combined with a power unit within said housing and comprising a pair of arcuate chambers defined Within the housing, fluid displacer means within each power chamber movable between advanced and retracted positions to form in each chamber a pair of alternately enlarging and diminishing volumes each adapted to receive and discharge a working fluid, all the volumes of said power unit being coupled in fluid communication to coolers of said fluid flow paths, means forming a driving connection coupled to move the fluid displacer means of said power unit harmonically in a predetermined phase relation with respect to the harmonic oscillations of the first named drive means.

15. Apparatus according to claim 13 wherein said other displacer unit comprises a power unit and further including means forming a driving connection coupled to move the displacer members of said other displacer unit harmonically to provide a volumetric displacement in said chambers in a predetermined phase relation.

16. Apparatus according to claim 9 further including fluid connections serving to form fluid paths between enlarging and diminishing volumes, each said path respectively serving to couple the diminishing volume of an associated one of said chambers to the enlarging volume of an associated one of said chambers to the enlarging volume of the same chamber, each of said paths including heat exchange means therein.

17. Apparatus according to claim 16 wherein said heat exchange means includes a fluid cooler for subtracting heat energy from fluid, a heater for adding heat energy to fluid, and a regenerator therebetween for transient storage of heat energy therein, and further including a power unit including fluid displacement means operably coupled to said oscillating means and movable between advanced and retracted positions to form a pair of enlarging and a pair of diminishing fluid volumes, all said volumes being in free fluid communication with a respective one of said coolers.

18. In an engine system of a type wherein the pressure of a working fluid in active portions of the engine system fluctuates above and below a mean pressure and wherein inactive portions of the system remain substantially at said mean pressure notwithstanding said fluctuations, speed regulating apparatus comprising means defining first and second expansible fluid volumes to respectively alternately enlarge and diminish for accepting and discharging fluid, means serving to fluid couple said first volume to said active portions to respond to the pressures of the Working fluid thereof, a reservoir of relatively incompressible fluid in fluid communication with said inactive portions to be subject to the mean pressure thereof, and flow control means for passing the relatively incompressible fluid from the reservoir into and out of said second volume to respectively decrease or increase the dead volume of the engine system by increasing or decreasing said first volume in response to changes in said second volume, said relatively incompressible fluid being passed under transitory pressure differentials existing between the inactive portions and the active portions of the engine system.

19. Speed regulating apparatus as defined in claim 18 wherein said flow control means includes a pair of fluid paths each containing a unidirectional fluid check valve, said check valves being respectively oriented to pass liquid in opposite directions with respect to said second volume, and a valve to be conditioned to fluid couple the reservoir to said second volume via one or the other of said check valves to feed liquid into or out of said second volume so as to vary said first volume to change the speed or power of said engine.

20. In an engine system of a type wherein the pressure of a working fluid in active portions of the engine system fluctuates above and below a mean pressure, speed regulating apparatus comprising means defining first and second expansible fluid volumes in fluid communication with each other to respectively alternately expand and contract for accepting and discharging hydraulic fluid, hydraulic fluid storage means in fluid communication with said active portions via means serving to provide a substantially constant mean fluid pressure source derived from said active portions of the engine system, means serving to fluid couple said first volume to said active portions to respond to the fluctuating pressures thereof, floW control means for passing a body of hydraulic fluid into or out of said second volume to respectively decrease or increase the active volume of the engine system by increasing or decreasing said first volume in response to changes in said second volume, said hydraulic fluid storage means being in fluid pressure transmitting communication with said second volume via said flow control means, said hydraulic fluid being passed to and from said second volume under transitory pressure differentials occurring between said relatively constant mean pressure of said storage means and the pressure fluctuations of the active portions of the engine system.

21. Speed regulating apparatus according to claim 20 wherein said means serving to provide a substantially constant mean fluid pressure source derived from the active portions of the engine system includes a flow restrictive impedance interposed between said fluid storage means and those active portions of the engine system subject to pressure fluctuations.

References Cited UNITED STATES PATENTS 2,990,681 7/1961 Wales 6024 3,370,418 2/1968 Kelly 60-24 3,413,815 12/1968 Grouryd 60-24 WILLIAM J. WYE, Primary Examiner US. Cl. X.R. 62-6 

